It is known in the art to provide a module in which an optical device such as a laser device and an electrical device such as an IC are integrated together on the same substrate (for example, refer to patent document 1 in the list shown below). In the module disclosed in patent document 1, an optical device and an electrical device for controlling the optical device are mounted on a silicon or like substrate. Further, an optical waveguide which is optically coupled to the optical device, and which directs light to the outside, is formed on the same substrate.
In the module disclosed in patent document 1, the optical device and the electrical device are both flip-chip mounted on the substrate. That is, the optical device and the electrical device, with bumps formed on their bottom faces, are placed on the substrate with the bumps contacting with electrodes, etc. formed on the substrate, and are pressed together under heat to accomplish metal bonding.
There is also known a technique for bonding an optical device such as a laser device to a substrate by surface activated bonding (for example, refer to patent document 2 in the list shown below). Surface activated bonding is a technique that activates material surfaces by removing inactive layers such as oxides, contaminants, etc. covering the material surfaces by plasma or other means, and that bonds the surfaces together at low temperatures by causing atoms having high surface energy to contact each other and by utilizing the adhesion forces acting between the atoms.
It is also known to provide a stacked-type semiconductor device which is constructed by stacking semiconductor chips one on top of another in order to increase the packing density of the semiconductor device (for example, refer to patent document 3). In the semiconductor device disclosed in patent document 3, a through-silicon via is formed in each semiconductor chip, and the stacked semiconductor chips are electrically connected together by the through-silicon vias and solder bumps.